To a rough ride in the sky. A number of passengers and crew members hurt when their flight from Denver to Billings, Montana, ran into severe turbulence just before landing and ABC's David Kerley has the story. Reporter: Just as the 737 from Denver was starting to descend for a landing in Billings, Montana, a violent sudden drop. Felt like something came up from the bottom and hit the bottom of the plane. And then stuff and people were flying all over the place. Reporter: United airlines described it as severe turbulence. The machine in front of me flew up out of his seat and hi the ceiling. Reporter: One passenger quoted as saying a flight attendant also hit the ceiling. One of those two hit so violently the roof lining cracked. The drop so forceful an infant flew from a mother's airports and landed in another seat nearby unharmed but scared. With three crew members hurt as well as a number of passengers, the captain declared a medal emergency. We're going to -- bleeding pretty badly and they can't get it to stop so they're requesting medal attention at the gate. White knuckle flying. Reporter: Once on the ground among the 114 passengers and 5 crew members, 3 flight attendants and 2 passengers were taken to the hospital. One taken to intensive care. Turbulence is not uncommon and often hits without warning hurting crew members the most. Every year turbulence injures on average 32 people in aircraft and more than two-thirds of those hurt are crew members. Now, of the five people taken to the hospital, four have been treated and released. Only that flight attendant is still hospitalized this morning and it's a tragic reminder when they tell you whether you're landing or taking off but during flight keep your seat belt buckled so you Tay in your seat in case there's turbulence like we saw yesterday.

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